Vanishing White Matter (VWM) disease is one of the most prevalent leukodystrophies, and is caused by mutations in any of the five subunits of eukaryotic translation initiation factor EIF2B. Even though many different kinds of EIF2B mutations have been identified, it is still unclear how these mutations cause the dramatic loss of myelin. One of the biggest problems has been the lack of a suitable experimental system in which to test the effects of EIF2B mutations on brain cells. Our initial study of VWM patient-derived cells was made possible by the exceedingly rare opportunity to isolate live glial precursor cells from the brain of a VWM patient. This study revealed a defect in astrocytes. But the lack of suitable patient samples limits our ability to study the cellular causes and consequently prevent us from finding a treatment for this devastating disease. It is the goal of this proposal to exploit inducible pluripotent stem cell (iPSC) technology to derive neural stem cell cultures from VWM-patient with distinct EIF2B complex mutations. These VWM-neural stem cells will be used to test the genotype-phenotype relationship with respect to astrocyte differentiation and function. Our preliminary data demonstrate that iPSCs can readily be derived from VWM-patient cells and that these patient- derived PSCs can be induced to differentiate into neural stem cells and astrocyte precursors. Mutations in EIF2B appear to cause increased cell death, and impair expression of some astroglial lineage proteins, including the astroglial lineage determinant CREB3L1. Because of the critical role of astrocytes in maintaining CNS homeostasis, our findings raise two important questions: (1) Do VWM patients with distinct EIF2B mutations exhibit the same astrocyte defect? (2) How does impairment of EIF2B disrupt astrocyte biology? To address these questions, we will: (Aim 1) establish and characterize inducible pluripotent stem (iPS) cell lines from different VWM-disease patients, and (Aim 2) use these cells to examine astroglial differentiation, reactive gliosis and the ability to support survival and differentiation of oligodendrocytes.